Lithographic-printing plate.



N0. 637,55l. Patented Nov. 2|, I899.

P. G. FRAUENFELDER.

LITHOGRAPHIC PRINTING PLATE.

Application filed Mar. 31, 1899.)

No Model.)

E55 & HWWHIMW'ILW.

PM BY ATTORNEYS.

PAUL GEORGE FRAUENFELDER, OF NEW YORK, N. Y., ASSIGNOR TO THE AMERICANLITHOGRAPHIC COMPANY, OF NEW YORK.

SPEQIFICATION forming part of Lettersfatent No. 637,551, dated November21, 1899.

Application filed March '31, 1899.

provide a new and improved lithographicprinting form which shall be freefrom some of the disadvantages hitherto inherent in such forms and whichshall at the same time be less expensive than forms usually employed;and the invention consists in providing the printing-forms with an inkand water carrying printing-surface of electrcdeposited zinc.

The accompanying drawings show my invention in its preferred form.

Figure 1 shows a lithographic-printing form cylindrical in shape, ofwhich a represents the'electrodeposit-ed zinc printing-surface, which ispartly broken away to show the cylinder 1), upon which said surface hasbeen electrodeposited. Fig. 2 is a vertical section of the same. Fig. 3shows a fiat lithographic-printing form, the letter a indicating theelectrodeposited zinc surface, which is partly broken away to show thesupportingplate 1), upon which the zinc is deposited. Fig. 4 is avertical section of the same. These forms may be of any desired shape orsize.

I'Ieretofo're stone has (been almost exclusively used as theprinting-surface in practical lithographic work, and metal has been butlittle, if at all, used with satisfactory results in spite of the greatcost, the inconvenience and expense of handling, and the other manifestdisadvantages of-stone and in spite of the attention that has beendirected toward making metal available for this pur pose, as evidencedby the patents granted therefor and otherwise. Zinc in the form ofsheets or plates has been experimented with probably more than any othermetal, but with little, if any, practical success. Among the reasons arethe following The ordinary rolled zinc sheets or plates of commercewhich have been heretofore the subject of such experiments have not asurface suitable for lithographic-printing purposes. The use of sandfilm is useful for the printing.

Serial No. 711,194. (No model.)

zinc surface cannotpractically be used with any reliability for printinga secondor third design Without cutting down or grinding down to asubstantially new level or surface and sand-blasting that new surfaceand preparing it, as before. Sandblasting is expensive, and the cuttingdownto a new level or surface is uot practicable. Zinc sheets or platessuch as have ordinarily been proposed for use have been very thinsayo'ne-sixtieth of an inch in thickness-in order to avoid the loss of agreat body of zinc, sinceonly the surface These thin plates,howevenwhile light to handle are the 'more liable to injury in handlingfrom the lack of rigidity,and every crinkle, bend, or inequality ofsurface shows in the printing.

In fact, if one of these thin zinc sheets or plates prepared as aprinting-surface with a design, upon its face is laid upon the bed of apress .it will almost invariably show slight bends,

swells, elevations, and depressions. These defect-s cannot be eliminatedby pressure or by hammering, for'such treatment would destroy the workupon the printing-surface. These evils have been sought to beremedied'as much as possible by tightly stretching the sheets over theirsupports; but they cannot be wholly eliminated in this way nor theireifects in the printing wholly counteracted. In order to increase theeffects of this stretching, the sheets have ordinarily been made as'thin as possible, but not with satisfactory results. Furthermore, thework is often worn off unevenly by the friction of the rollers, &c., inthe printing operation at .the places where the zinc sheet or platesprings up, swells, crinkles, or bends. Again, these thin zinc sheetswill soon tear or break along the lines where they are bent andstretched over the edges of the bed and so become useless for that pressbecause too small. A sufiicient 5 thickness or body of zinc in thesheets to render them reliably rigid and so to avoid the evils abovereferred to would end either in the loss of the entire mass of zincafter practically only one or two uses of the printing- KOO a .es7,551

surface thereof or in the necessity of repeatedly resorting to theimpracticable grinding and sand-blasting process. In the case ofcylindrical or other curvilinear-shaped zinc sheets most of the aboveevils would be greatly exaggerated and others supervene, arising fromthe increased dilliculty of securing 1miformity of surface in suchshapes. Again, the zinc sheets of commerce are quite impure, andespecially is this true of very thin sheets such as must be used inlithography, for in such case lead has to be used in admixture with thezinc to give rollability. Chemicallypure zinc is expensive and would bedifficult to roll out into thin sheets successfully and economically.These considerations suggest some of the causes for the observed factthat in experimenting with metals, including zinc as ordinarilyattempted to be used for lithographic-printing purposes, many defectsand imperfections are exhibited in comparison wit-h stone, such as falsetinting, smearing, rapid deterioration, lack of porosity, oxidation,the. My invention obviates these difiiculties, for I have discovered acharacter of zinc surface that is at once--that is to say,

without the necessity of resorting to the sandblasting processor toanyproccss of bending or stretching or hammering- -suitable for andespecially adapted to receive an ink transfer or design after thelithographic manner and to act, after being suitably developed, as alithographic printing surface therefor and more perfectly adaptedthereto than has been any metal surface heretofore practicallyobtainable. I have discovered that zinc when deposited electrolyticallyunder suitable control is adherent and coherent, is suitahlyporous andabsorbent, is even and uniform, without corrugations, seams, bends,streaks, ruts,

- nodules, or other like imperfections, and has a surface conditionadmirahl y adapted to the requirements of lithographic transferring andsubsequent printing, and this at once and without the necessity ofmechanical preparation of the surface, such as sand-blasting, bending,stretching, hammering, the. Such an electrolytically-deposited zincsurface is also at once and without the intervention of any transfer ortransferring process suitable to receive a design and be printed fromdirectly in the lithographic manner. More.-

over, azinc surface thus obtained is readily removable from the metallicbacking and can be economically applied thereto an indefinite number oftimes.

In practicing my invention in its preferred form I have found thefollowing procedure effective: A baekingof suitable metal-eopper, forexample-and of any desired ,size or shape-flat, cyl ndrical, orotherwise-and of suitable rigidity is evened and polished as to itsouter surface and thoroughlycleaned and then mounted in a suitable zincelectrolytic bath, and after the application of a suitable current forthe length of time necessary to deposit an even, continuous, adherent,co-

IlGlElll], and absorbent coating of zinc of the requisite thickness toconstitute a lithographic-printing surface the plate is removed from thebath, thoroughly washed off with water, and is then at once ready toreceive,

for example, an ink transfer or design after printi ng-surface may beattained by a manipu-' lation of the rigid metallic backing, the zincprinting-s11 rface being applied electrolytically and conforming theretoafter such shape has been exactly and satisfactorily attained. It isalso of advantage that there should be not only no bending or stretchingor other such change in the printing-surface after the same has beenetched or prepared for printing, but also that there should be noslipping or moving of that printing-surface on or to or from its metalbacking under the pressure of the rollers, cylinders, &c., in thevarious steps of printing.

The present in vent-ion is pecnliarlyadvantageous in connection withcylindrical printin g-surfaces. In fact, it makes the use of cylindricalprinting-surfaces practically possible, and its advantages areconspicuously present in such combination and .application, sincethereby a continuous, seamless, adherent, co-

herent, absorbent, and readily-removable surface may beeeonomically'obtained.

The plating-bath and the current and all the details of the plating mustof course be so manipulated and controlled as to yield the propercharacter of zinc deposit; In practice I have found the followingdetails of manipulative treatment in a plating-bath effective: \Vith aplate forty (40) inches by thirty ('30) and a suitably sized andarranged bath I employ as the electrolyte to one hundred pounds of watertwenty-five (25) pounds of sulfate of'zine and three (3) ounces of gum.-arabic. A current measuring eight (8) volts and thirty (30) amperes isfurnished by a dynamo. When the plating is completed, the printing-formis removed from the bath and is plunged in a one-per-ccnt'. bathofeyanid of potassium and is thoroughly washed off. It is then at oncefitted to receive a design. The zinc surface, after the design has beenmade upon it or transferred to it, is developed into a printing surfaceplanographic throughout, the electrodepositcd zinc performing both theink-carrying and the water-carrying functions. Theelectrolyticallydeposited zinc surface is a uniform pianographic surfacecovering the whole of the printing-form prior to the prod uein gortransfcrring of the design to it, and,every part of it is capable ofreceiving the ink of such transfor or design, and the parts which doreceive the ink of the transfer or design become and are, after thedevelopment of the surface as a whole into a lithographimprintingsurface,

roe

also remain in substantially the original planographi'c level, butbecome the watercarrying parts or surface. In other words, by the modeof development common in lithographic printing the printing-surface as awhole after such developmcutis still aplanographic surface and theelectrolytically-deposited zinc performs both the ink-carrying and thewater-carrying functions of the printing-surface What I claim as new,and desire to secure by Letters Patent, is-

A lithographic-printing form having. a design developed upon itsprinting-surface in the lithographic manner, the ink-carrying andwater-carrying portions of which printing-surface consist ofelectrolytically-deposited zinc.

In testimony whereof I have name to this specification in the twosubscribing witnesses.

PAUL GEORGE FRAUJ'LFEEDER.

signed my m'esenco of Witnesses:

EDWIN SEGER, SIDNEY MANN.

